<?php

class Captcha_Adapter_Recaptcha extends Captcha_Adapter
{

	const RECAPTCHA_API_SERVER = "http://www.google.com/recaptcha/api";
	const RECAPTCHA_API_SECURE_SERVER = "https://www.google.com/recaptcha/api";
	const RECAPTCHA_VERIFY_SERVER = "www.google.com";

	protected $_publicKey = RECAPTCHA_PUBLIC_KEY;

	protected $_privateKey = RECAPTCHA_PRIVATE_KEY;

	protected $_SSL = false;

	/**
	 * @return void
	 */
	public function __construct()
	{
		
	}

	/**
	 * Encodes the given data into a query string format
	 * @param $data - array of string elements to be encoded
	 * @return string - encoded request
	 */
	function _recaptcha_qsencode($data)
	{
		$req = "";
		foreach ($data as $key => $value)
			$req .= $key . '=' . urlencode(stripslashes($value)) . '&';

		// Cut the last '&'
		$req = substr($req, 0, strlen($req) - 1);
		return $req;
	}

	/**
	 * Submits an HTTP POST to a reCAPTCHA server
	 * @param string $host
	 * @param string $path
	 * @param array $data
	 * @param int port
	 * @return array response
	 */
	function _recaptcha_http_post($host, $path, $data, $port = 80)
	{

		$req = $this -> _recaptcha_qsencode($data);

		$http_request = "POST $path HTTP/1.0\r\n";
		$http_request .= "Host: $host\r\n";
		$http_request .= "Content-Type: application/x-www-form-urlencoded;\r\n";
		$http_request .= "Content-Length: " . strlen($req) . "\r\n";
		$http_request .= "User-Agent: reCAPTCHA/PHP\r\n";
		$http_request .= "\r\n";
		$http_request .= $req;

		$response = '';
		if (false == ($fs = @fsockopen($host, $port, $errno, $errstr, 10)))
		{
			die('Could not open socket');
		}

		fwrite($fs, $http_request);

		while (!feof($fs))
			$response .= fgets($fs, 1160);
		// One TCP-IP packet
		fclose($fs);
		$response = explode("\r\n\r\n", $response, 2);

		return $response;
	}

	/**
	 * Gets the challenge HTML (javascript and non-javascript version).
	 * This is called from the browser, and the resulting reCAPTCHA HTML widget
	 * is embedded within the HTML form it was called from.
	 * @param string $pubkey A public key for reCAPTCHA
	 * @param string $error The error given by reCAPTCHA (optional, default is null)
	 * @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)

	 * @return string - The HTML to be embedded in the user's form.
	 */
	function getHtml($error = null)
	{
		$pubkey = $this -> _publicKey;
		$use_ssl = $this -> _SSL;

		if ($pubkey == null || $pubkey == '')
		{
			die("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
		}

		if ($use_ssl)
		{
			$server = self::RECAPTCHA_API_SECURE_SERVER;
		}
		else
		{
			$server = self::RECAPTCHA_API_SERVER;
		}

		$errorpart = "";

		if ($error)
		{
			$errorpart = "&amp;error=" . $error;
		}

		return '<script type="text/javascript" src="' . $server . '/challenge?k=' . $pubkey . $errorpart . '"></script>';
	}

	/**
	 * Calls an HTTP POST function to verify if the user's guess was correct
	 * @param string $privkey
	 * @param string $remoteip
	 * @param string $challenge
	 * @param string $response
	 * @param array $extra_params an array of extra variables to post to the server
	 * @return ReCaptchaResponse
	 */
	function recaptcha_check_answer($extra_params = array())
	{

		$remoteip = $_SERVER["REMOTE_ADDR"];
		$challenge = $_REQUEST["recaptcha_challenge_field"];
		$response = $_REQUEST["recaptcha_response_field"];

		$privkey = $this -> _privateKey;

		if ($privkey == null || $privkey == '')
		{
			die("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
		}

		if ($remoteip == null || $remoteip == '')
		{
			die("For security reasons, you must pass the remote ip to reCAPTCHA");
		}

		//discard spam submissions
		if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0)
		{
			return false;
		}

		$response = $this -> _recaptcha_http_post(self::RECAPTCHA_VERIFY_SERVER, "/recaptcha/api/verify", array(
			'privatekey' => $privkey,
			'remoteip' => $remoteip,
			'challenge' => $challenge,
			'response' => $response
		) + $extra_params);

		$answers = explode("\n", $response[1]);

		return (bool)(trim($answers[0]) == 'true');
	}

	/**
	 * gets a URL where the user can sign up for reCAPTCHA. If your application
	 * has a configuration page where you enter a key, you should provide a link
	 * using this function.
	 * @param string $domain The domain where the page is hosted
	 * @param string $appname The name of your application
	 */
	function recaptcha_get_signup_url($domain = null, $appname = null)
	{
		return "https://www.google.com/recaptcha/admin/create?" . _recaptcha_qsencode(array(
			'domains' => $domain,
			'app' => $appname
		));
	}

	function _recaptcha_aes_pad($val)
	{
		$block_size = 16;
		$numpad = $block_size - (strlen($val) % $block_size);
		return str_pad($val, strlen($val) + $numpad, chr($numpad));
	}

	/* Mailhide related code */

	function _recaptcha_aes_encrypt($val, $ky)
	{
		if (!function_exists("mcrypt_encrypt"))
		{
			die("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.");
		}
		$mode = MCRYPT_MODE_CBC;
		$enc = MCRYPT_RIJNDAEL_128;
		$val = _recaptcha_aes_pad($val);
		return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
	}

	function _recaptcha_mailhide_urlbase64($x)
	{
		return strtr(base64_encode($x), '+/', '-_');
	}

	/* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
	function recaptcha_mailhide_url($pubkey, $privkey, $email)
	{
		if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null)
		{
			die("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " . "you can do so at <a href='http://www.google.com/recaptcha/mailhide/apikey'>http://www.google.com/recaptcha/mailhide/apikey</a>");
		}

		$ky = pack('H*', $privkey);
		$cryptmail = _recaptcha_aes_encrypt($email, $ky);

		return "http://www.google.com/recaptcha/mailhide/d?k=" . $pubkey . "&c=" . _recaptcha_mailhide_urlbase64($cryptmail);
	}

	/**
	 * gets the parts of the email to expose to the user.
	 * eg, given johndoe@example,com return ["john", "example.com"].
	 * the email is then displayed as john...@example.com
	 */
	function _recaptcha_mailhide_email_parts($email)
	{
		$arr = preg_split("/@/", $email);

		if (strlen($arr[0]) <= 4)
		{
			$arr[0] = substr($arr[0], 0, 1);
		}
		else
		if (strlen($arr[0]) <= 6)
		{
			$arr[0] = substr($arr[0], 0, 3);
		}
		else
		{
			$arr[0] = substr($arr[0], 0, 4);
		}
		return $arr;
	}

	/**
	 * Gets html to display an email address given a public an private key.
	 * to get a key, go to:
	 *
	 * http://www.google.com/recaptcha/mailhide/apikey
	 */
	function recaptcha_mailhide_html($pubkey, $privkey, $email)
	{
		$emailparts = _recaptcha_mailhide_email_parts($email);
		$url = recaptcha_mailhide_url($pubkey, $privkey, $email);

		return htmlentities($emailparts[0]) . "<a href='" . htmlentities($url) . "' onclick=\"window.open('" . htmlentities($url) . "', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;\" title=\"Reveal this e-mail address\">...</a>@" . htmlentities($emailparts[1]);

	}

}
